JP5733974B2 - CO shift conversion system and method, coal gasification power plant - Google Patents

Description

  The present invention relates to a CO shift conversion system and method capable of efficiently performing a CO shift reaction, and a coal gasification power plant.

  Effective use of coal has attracted attention as one of the trump cards in recent energy problems. On the other hand, advanced technology such as coal gasification technology and gas purification technology is required to convert coal as an energy medium with high added value. A coal gasification combined power generation system that generates power using this gasification gas has been proposed (Patent Document 1).

  This integrated coal gasification combined cycle (IGCC) is a combination of a gas turbine and a steam turbine that converts coal into combustible gas in a high-temperature and high-pressure gasification furnace and uses the gasification gas as fuel. A system that generates electricity.

Most of the hydrocarbon compounds present in the coal gasification gas (product gas) are carbon monoxide (CO), and carbon dioxide (CO ₂ ) and hydrocarbons (CH ₄ , CnHm) are only a few percent. As a result, in order to recover the CO ₂ is converted to CO present in the product gas must be converted to CO _2, while adding water vapor (H ₂ O), the shift catalyst to CO ₂ by the following reaction It has been proposed to do.
CO + H ₂ O⇔CO ₂ + H ₂ +40.9 kJ / mol (exothermic reaction) (1)

Up to now, based on the knowledge of shift reaction in the chemical industry, the reaction (1) has been advanced by sufficiently increasing the steam addition ratio (H ₂ O / CO) at the CO shift reactor inlet. Thus, the desired CO → CO ₂ conversion rate can be obtained.

Japanese Patent Laid-Open No. 2004-331701

On the other hand, an IGCC plant equipped with a CO ₂ recovery facility is a power plant, and it is necessary to give consideration to the environment (reduction of CO ₂ emissions) and to emphasize plant power generation efficiency.
That is, the reduction of the amount of steam extracted from the HRSG (exhaust heat recovery boiler) planned as the steam addition source for the steam addition ratio (H ₂ O / CO) at the shift reactor inlet improves the plant efficiency. Since it is an important factor above, it is required to reduce the medium-pressure steam from HRSG as much as possible from the viewpoint of increasing the power generation efficiency.

A CO shift catalyst (for example, molybdenum sulfide (MoS ₃ )) is used for the shift reaction in the shift converter, but when the amount of water replenished from the outside is small, coking (carbon deposition) occurs on the catalyst surface and the catalyst deteriorates. Cause the conversion efficiency to decrease.

  In view of the above problems, an object of the present invention is to provide a CO shift conversion system and method, and a coal gasification power plant capable of efficiently performing a CO shift reaction without catalyst deterioration even when the amount of water vapor is small. .

A first invention of the present invention for solving the above-mentioned problems includes a CO shift conversion device that has a CO shift catalyst using molybdenum sulfide and converts CO in the product gas into CO ₂ , and the CO shift conversion A water vapor supply means provided on the upstream side of the apparatus for supplying water vapor required for converting CO in the generated gas into CO _2; and a water spray for supplying water spray to the generated gas supplied with water vapor via a mixer. includes a CO shift conversion unit having a supply means, the CO shift converter unit is multistage connected in series at least two supplies when hydrogen sulfide concentration in the product gas is 100ppm or less, a water spray into the mixer It is in the CO shift conversion system characterized by this.

A second invention is the CO shift conversion system according to the first invention, further comprising hydrogen sulfide supply means for supplying hydrogen sulfide when the concentration of hydrogen sulfide in the product gas is 100 ppm or less .

A third invention is a gasification furnace to obtain a product gas of coal is gasified, the CO shift conversion system of the first or second invention for converting CO in the product gas to CO _2, CO ₂ in the CO shifted gas CO ₂ recovery device having a CO ₂ absorption tower for recovering gas and an absorption liquid regeneration tower for regenerating the absorption liquid, gas turbine equipment having a combustor for burning purified gas, and heat of combustion exhaust gas of the gas turbine equipment A coal gasification power plant comprising an exhaust heat recovery boiler (HRSG) that recovers energy and a steam turbine facility that generates power using steam recovered by the exhaust heat recovery boiler.

A fourth invention uses the CO shift conversion system according to the first or second invention, and uses the CO shift conversion system according to claim 1 or 2, and when the hydrogen sulfide concentration in the product gas is 100 ppm or less, the supplied to the mixer in the CO shift conversion method characterized by suppressing the temperature increase of the CO shift catalyst.

A fifth invention is the CO shift conversion method according to the fourth invention, further comprising hydrogen sulfide supply means for supplying hydrogen sulfide when the concentration of hydrogen sulfide in the product gas is 100 ppm or less .

  According to the present invention, by supplying water spray, even when the amount of water vapor is small, there is no catalyst deterioration and the CO shift reaction can be performed efficiently. Therefore, the CO shift reaction can be performed efficiently without increasing the supply amount of water vapor. Thereby, supply_amount | feed_rate of the extraction intermediate pressure steam conventionally supplied from HRSG can be reduced. As a result, the power generation efficiency is improved and the energy efficiency of the entire plant can be improved.

FIG. 1 is a schematic diagram of a CO shift conversion system according to the first embodiment. FIG. 2 is a relationship diagram between the catalyst temperature of the CO shift converter and (H ₂ S / H ₂ O) ³ . FIG. 3 is a schematic diagram of a coal gasification power plant including the energy recovery device according to the second embodiment. FIG. 4 is a schematic diagram of a CO shift conversion system according to the third embodiment.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

A CO shift conversion system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a CO shift conversion system according to the first embodiment.
As shown in FIG. 1, a CO shift conversion system 10A according to the present embodiment includes a CO shift catalyst 11, a CO shift conversion device 13 that converts CO in the product gas 12 into CO ₂ , and the CO shift conversion A water vapor supply means 15 provided upstream of the apparatus 13 for supplying the water vapor 14 into the product gas 12, and a water spray supply means 18 for supplying the water spray 16 by the mixer 17 after the water vapor 14 is supplied. The CO shift conversion unit 20 is provided, and at least two or more CO shift conversion units 20 are connected in series in series. In FIG. 1, reference numeral 21 denotes an H ₂ S concentration meter, 22 denotes a thermometer, 23 denotes a CO shift gas, and V ₁ and V ₂ denote valves.

In the present invention, even when the hydrogen sulfide (H ₂ S) concentration in the product gas 12 is low, by sufficiently supplying the water spray 16 from the water spray supply means 18, the temperature rise caused by the exothermic reaction of the CO shift reaction can be reduced. It is possible to suppress the deterioration of the catalyst. The mixing of the water spray 16 using the mixer 17 without supplying it directly into the product gas 12 is because water droplets are sufficiently vaporized to prevent deterioration of the catalyst provided on the downstream side. Provided.

This is because when the molybdenum sulfide concentration is low, when the temperature in the CO shift conversion device 13 is about 250 ° C., for example, the catalyst temperature rises due to the exothermic reaction resulting from the CO shift conversion reaction. To molybdenum oxide (MoO ₃ ), and then coking occurred and the catalytic function was not exhibited.

Here, FIG. 2 shows a relationship diagram between the catalyst temperature of the CO shift converter and (H ₂ S / H ₂ O) ³ . According to FIG. 2, it is confirmed that molybdenum sulfide (MoS ₃ ) changes to molybdenum oxide (MoO ₃ ) in a region where the catalyst temperature is lower as the hydrogen sulfide concentration is lower. Therefore, in the present invention, when the concentration of molybdenum sulfide (MoS ₃ ) is as low as 100 ppm or less, for example, the temperature in the CO shift converter 13 is obtained, and the hydrogen sulfide in the product gas 12 introduced into the CO shift converter 13 is obtained. By calculating the concentration with the H ₂ S densitometer 21, (H ₂ S / H ₂ O) ³ shown in FIG. 2 can be obtained by calculation. As a result, the amount of water input to be a stable region of molybdenum sulfide is determined. Can be sought. Thereby, since molybdenum sulfide exists stably, CO shift conversion can be performed efficiently.

Here, in the present invention, the case where the concentration of hydrogen sulfide (H ₂ S) is as low as 100 ppm or less is 1 × 10 ⁻¹² when water is 1, as shown in FIG. 2, corresponding to this. This is because the temperature is 325 ° C., and if the temperature is lower than that, the catalyst stable region becomes extremely small, and coking (carbon deposition) occurs on the catalyst surface, causing catalyst deterioration. Therefore, in the present invention, the case where the molybdenum sulfide concentration is low is 100 ppm.
Note that the boundary line between the MoS ₃ stable region and the MoO ₃ stable region slightly changes depending on the particle diameter of the catalyst.

  The multi-stage connection is made by suppressing the temperature rise by dispersing the catalyst and performing CO shift conversion little by little.

  In the present embodiment, the CO shift conversion unit 20 is illustrated as having two stages, but may be provided with two stages, three stages, etc. as necessary. Therefore, when the concentration of hydrogen sulfide in the product gas 12 is even lower, for example, 10 ppm, the number of multistage connections may be increased. Here, the concentration of hydrogen sulfide in the product gas 12 greatly depends on the production location, production lot, etc. of the raw coal supplied to the gas furnace of the coal gasification power plant (IGCC), for example. When changing the above, it is sufficient to pay attention to the selection of the number of stages of the CO shift conversion unit 20 in particular.

  According to this embodiment, when the concentration of hydrogen sulfide in the product gas 12 is low and the catalyst temperature rises, the amount of water vapor is reduced by supplying the water spray 16 without changing the temperature of the water vapor 14. Even if the amount is small, the catalyst is not deteriorated and the CO shift reaction can be performed efficiently. Therefore, the CO shift reaction can be efficiently performed without increasing the supply amount of the water vapor 14.

A coal gasification power plant including an energy recovery device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a schematic diagram of a coal gasification power plant including the energy recovery device according to the second embodiment.
As shown in FIG. 3, a coal gasification power plant 50 equipped with an energy recovery device converts a gasification furnace 52 that gasifies coal 51 to obtain a product gas 12 and converts CO in the product gas 12 into CO ₂ . a CO shift conversion system 10A, a desulfurization unit 53 for recovering the sulfur (S) content in the CO shifted gas 23, a CO ₂ recovery device 54 for recovering CO _2, with purified gas 55 from the CO ₂ recovery apparatus 54 Combined power generation facilities for combined power generation (gas turbine equipment with a combustor for refining combustion, exhaust heat recovery boiler (HRSG) that recovers thermal energy of combustion exhaust gas from gas turbine equipment, and steam recovered by an exhaust heat recovery boiler) A steam turbine facility 56 for generating power from the generator 67. In FIG. 3, reference numeral 60 is air, 61 is an air separator, 62 is oxygen obtained by the air separator 61, 63 is nitrogen, 64 is recovered H2S gas recovered by the desulfurizer 53, and 65 is sulfur (S). The fraction recovery device, 66 is the recovered CO ₂ gas, 67 is the CO ₂ compressor, and 68 is the slag.

  In the present embodiment, since the CO shift conversion system 10A of the first embodiment is applied as the CO shift conversion system, the supply amount of the extraction medium pressure steam 69 that has been supplied from the exhaust heat recovery boiler (HRSG) of the combined power generation facility 56 conventionally. Part (about 15%) can be supplemented, and the extraction medium pressure steam 69 can be reduced accordingly. As a result, the power generation efficiency is improved and the energy efficiency of the entire plant can be improved.

  Thus, according to the present embodiment, in the CO shift conversion system 10A, even when the concentration of hydrogen sulfide existing in the product gas 12 is low, the catalyst is prevented from deteriorating by supplying water spray. The CO shift conversion can be performed, and by supplying the water spray, a part of the extraction intermediate pressure steam 69 in the CO shift conversion device of the CO shift conversion system 10A can be supplemented. The supply amount of the extraction medium pressure steam 69 from the heat recovery boiler (HRSG) can be reduced, which contributes to improvement of power generation efficiency.

A CO shift conversion system according to an embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a schematic diagram of a CO shift conversion system according to the third embodiment.
As shown in FIG. 4, the CO shift conversion system 10B according to the present embodiment is an H ₂ S supply means 31 for supplying hydrogen sulfide (H ₂ S) to the mixer 17 in the CO shift conversion system 10A of the first embodiment. Is provided.

In the first embodiment, the water spray 16 is supplied to suppress the temperature increase of the CO shift catalyst 11. However, in this embodiment, when the H ₂ S concentration in the product gas 12 is extremely low, a separate H _{2 is used.} S is supplemented. The supplied H ₂ S reuses the recovered H ₂ S gas 64 recovered by the desulfurization device 53 in the coal gasification power plant 50 shown in FIG.

In particular, when a sudden change in the H ₂ S concentration is predicted due to a change in the brand of the coal 51 supplied to the gas furnace 52, the response by changing the temperature and water vapor may be difficult from the viewpoint of responsiveness due to heat capacity. In such a case, by adding the hydrogen sulfide concentration so as to be a predetermined amount (for example, 100 ppm), the molybdenum sulfide (MoS ₃ ) passes from the stable region to the unstable region to stabilize the MoO _3. Reaching the region is prevented, the catalyst function can be sufficiently exerted, and a good CO shift reaction can be performed.

  As described above, according to the CO shift conversion system and method and the coal gasification power plant according to the present invention, even when the amount of water vapor is small, there is no catalyst deterioration, and the CO shift reaction can be performed efficiently. It can contribute to improvement.

10A, 10B CO shift conversion system 11 CO shift catalyst 12 Product gas 13 CO shift conversion device 14 Water vapor 15 Water vapor supply means 16 Water spray 17 Mixer 18 Water spray supply means 20 CO shift conversion section

Claims (5)

A CO shift conversion device having a CO shift catalyst using molybdenum sulfide and converting CO in the product gas to CO ₂ ;
A water vapor supply means provided on the upstream side of the CO shift converter, for supplying water vapor required for converting CO in the produced gas into CO ₂ ;
Includes a CO shift conversion unit comprising a supply water spray supply means generating gas supplied steam water spray through a mixer,
The CO shift conversion units are connected in multiple stages in series of at least two or more,
A CO shift conversion system that supplies water spray to a mixer when the concentration of hydrogen sulfide in the product gas is 100 ppm or less. In claim 1,
A CO shift conversion system comprising hydrogen sulfide supply means for supplying hydrogen sulfide when the concentration of hydrogen sulfide in the product gas is 100 ppm or less. A gasification furnace that gasifies coal to obtain product gas;
A CO shift conversion system according to claim 1 or 2 for converting CO in the product gas into CO ₂ ;
A CO ₂ recovery device comprising a CO ₂ absorption tower for recovering CO ₂ in the CO shift gas and an absorption liquid regeneration tower for regenerating the absorption liquid;
A gas turbine facility equipped with a combustor for burning purified gas;
An exhaust heat recovery boiler (HRSG) for recovering the thermal energy of the combustion exhaust gas of the gas turbine equipment,
A coal gasification power plant comprising a steam turbine facility that generates electricity using steam recovered by an exhaust heat recovery boiler. Using the CO shift conversion system according to claim 1 or 2,
A CO shift conversion method characterized in that when the concentration of hydrogen sulfide in the product gas is 100 ppm or less, water spray is supplied to a mixer to suppress the temperature increase of the CO shift catalyst. In claim 4,
A CO shift conversion method comprising hydrogen sulfide supply means for supplying hydrogen sulfide when the concentration of hydrogen sulfide in the product gas is 100 ppm or less.

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